1. Technical Field
The present invention relates in general to fabricating earth boring bits and, in particular, to an improved system, method, and apparatus for brazing together the components of cutters for fixed cutter bits.
2. Description of the Related Art
Rotary drill bits are commonly used for drilling boreholes or wells in earth formations. One type of rotary drill bit is the fixed cutter bit or “drag bit,” which typically includes a plurality of cutting elements secured to a face region of a bit body. Generally, the cutting elements of a fixed cutter type drill bit have either a disk shape or a substantially cylindrical shape. A hard, super abrasive material, such as mutually bonded particles of polycrystalline diamond, may be provided on a substantially circular end surface of each cutting element to provide a cutting surface. Such cutting elements are often referred to as “polycrystalline diamond compact” (PDC) cutters.
Typically, the cutting elements are fabricated separately from the bit body and secured within pockets formed in the outer surface of the bit body. A bonding material such as an adhesive or, more typically, a braze alloy may be used to secured the cutting elements to the bit body. The fixed cutter drill bit may be placed in a borehole such that the cutting elements are adjacent the earth formation to be drilled. As the drill bit is rotated, the cutting elements scrape across and shear away the surface of the underlying formation.
The bit body includes wings or blades, which are separated by junk slots. Internal fluid passageways extend between the face of the bit body and a longitudinal bore, which extends through the steel shank and partially through the bit body. A plurality of PDC cutters are provided on the face of the bit body. The PDC cutters may be provided along the blades within pockets formed in the face of the bit body.
The PDC cutters may be bonded to the bit body after the bit body has been cast by, for example, brazing, mechanical affixation, or adhesive affixation. Alternatively, the PDC cutters may be provided within a mold and bonded to the bit body during infiltration or furnacing of the bit body if thermally stable synthetic diamonds, or natural diamonds are employed. However, the high temperature ranges used to fabricate the bits can change the properties of the metals and other materials used. Thus, an improved system for joining the cutting elements to fixed cutter bits that overcomes the limitations of conventional processes would be desirable.